1. Field of the Invention
The present invention pertains to a transceiver. The invention more particularly concerns a transceiver that is mountable to a surface of a printed circuit board.
2. Discussion of the Background
A transceiver is a device that contains at least one opto-electronic receiver and at least one opto-electronic transmitter. An opto-electronic transmitter receives electrical signals, converts them to light signals, and then transmits the light signals. An opto-electronic receiver receives light signals, converts them to electrical signals, and then transmits the electrical signals. Known transceivers are soldered to printed circuit boards where their pins and posts extend through through holes formed in the printed circuit board or the transceivers are plugged into receptacles which are in turn mounted to a printed circuit board.
In order to save space, the use of a receptacle mounted to a printed circuit board is not acceptable and in other situations a printed circuit board does not utilize through holes into which pins may be projected and secured to the printed circuit board. Such environmental constraints require that a new mounting structure be formulated for attaching a transceiver to a printed circuit board.
Additionally, another problem is present with the use of known transceivers. Typically, the manufacturer of the transceiver is different than the manufacturer of the host device into which the transceiver is incorporated. Often times, this situation requires the use of additional electronic components which are mounted on the printed circuit board between the transceiver and the remainder of the printed circuit board so as to match the impedance of the transceiver to the electronics on the remainder of the printed circuit board. If the impedances are not matched, the system does not operate at its maximum potential since the flow of energy flowing from the transceiver to the host device and from the host device to the transceiver is restricted. The total cost of the additional electronic components required for the impedance matching includes the purchase cost of the additional electronic components, the storage cost of keeping the additional electronic components in inventory, and the labor cost of installing the additional electronic components. Furthermore, the additional electronic components occupy space, thus increasing the size of the host device, which is not desirable.
It is an object of the invention to provide a transceiver having a reduced size as compared to known transceivers.
It is a further object of the invention to provide a transceiver which is mountable to a surface of a printed circuit board.
It is another object of the invention to provide a transceiver having a controlled impedance electrical connection so that matching electronics are not necessary on or near the printed circuit board and so that the performance of the host device system, including the transceiver, is maximized.
It is another object of the invention to provide a transceiver having a connector or contacts which provide the function of impedance matching by adjusting the geometry of the conductors.
In one form of the invention the transceiver includes a housing, a transmitting optical sub-assembly mounted in the housing, a receiving optical sub-assembly mounted in the housing, a first electrical connector associated with the transmitting optical sub-assembly, a second electrical connector associated with the receiving optical sub-assembly, and an electro-magnetic shield mounted on the housing. The housing includes a first fiber optic connector receptacle, a second fiber optic connector receptacle, and a first side, and the housing is made of an electrically conductive material. The housing further includes a first alignment post and a second alignment post both of which are attached to the first side of the housing. The transmitting optical sub-assembly is associated with the first fiber optic connector receptacle. The receiving optical sub-assembly is associated with the second fiber optic connector receptacle. The first electrical connector projects from the housing and has a first plurality of contacts. A first contact of the first plurality of contacts is electrically grounded to the housing. The second electrical connector projects from the housing and has a second plurality of contacts. A second contact of the second plurality of contacts is electrically grounded to the housing. Additionally, so as to make the transceiver surface mountable to a host device printed circuit board, the side of the housing, a first portion of the first plurality of contacts, and a second portion of the second plurality of contacts substantially exist in a first plane. The electro-magnetic shield mounted on the housing prevents electro-magnetic fields from passing between the housing and a host device panel cut-out.
In another form of the invention, the transceiver contains the features described above and further includes the features of the first plurality of conductors and the second plurality of conductors being configured so as to substantially match an impedance of the transceiver with an impedance of the host device.
In another form of the invention, the transceiver contains the features described above and further includes the features of a first dielectric material substantially positioned between each contact of the first plurality of contacts, and a second dielectric material substantially positioned between each contact of the second plurality of contacts.
Another form of the invention includes a method of mounting a transceiver to a printed circuit board of a host device, where the printed circuit board of the host device is substantially flat. The method includes the steps of placing the transceiver on the surface of the printed circuit board of the host device so that a side of the transceiver contacts the surface of the printed circuit board of the host device and so that contacts of the transceiver contact the surface of the printed circuit board of the host device; grounding a chassis of the transceiver of the printed circuit board of the host device; and soldering the contacts of the transceiver to the printed circuit board of the host device.
Thus, the invention achieves the objectives set forth above. The invention provides a transceiver which is compact and incorporates an impedance matching electrical connection.